The effects of eggshell conductivity on hatchery performance and the relative risk assessment of translucent eggshell in breeders

An experiment was designed to determine whether translucent eggshells could negatively affect egg weight loss and incubation results. Internal and external egg quality parameters and microstructural shell differences were assessed. A total of 360 hatching eggs were obtained from a 54-week-old (Hy-Line) laying hen breeding flock. The eggs were divided into two groups: the first group consisted of eggs with translucent shells (TE) and large, numerous clear spots when candled; the second group, the control group (C), consisted of normal eggs without shell defects. The eggs from each group were randomly placed into incubator trays and incubated under standard incubation conditions. Both the eggshell conductivity and the specific eggshell conductivity were significantly higher in eggs with a translucent shell than in the control eggs. The proportion of shell in normal eggs was significantly higher than in TE eggs. TE Eggs had a higher relative weight loss during the first 7 and 18 days of incubation than the control eggs. An analysis of SEM images of translucent and normal eggshells revealed that normal eggs had a more regular formation of the mammillary layers at both the equator and the blunt ends. The percentage of fertilised eggs that hatched in the TE group was significantly lower than in the C group. The hatching window differed significantly between translucent and normal eggs. Chicks from TE eggs hatched earlier than chicks in eggs with a normal eggshell. It was concluded that it might be advisable not to use eggs with large and intense translucent spots for breeding. However, if this type of egg is to be used, excessive moisture loss should be prevented by storing them for a shorter period of time and increasing the relative humidity in the egg storage room and incubators.